DE939719C - Tube made of non-weldable plastic - Google Patents

Description

The invention relates to the manufacture of pipelines for conveying primarily more aggressive Media from pipes made of a non-weldable plastic and here in particular on the design of the pipe ends to make them weldable and thus the individual pipes to the pipeline with one another to be able to weld.

In order to convey aggressive media, pipes are often used, the pipes of which consist of a weldable plastic. So far, thermoplastic materials have primarily been used for this purpose Polyvinyl chloride and polyethylene used, which have excellent weldability, so that the individual pipes are connected to one another by welding to form an absolutely tight pipeline can be. Recently, however, aggressive media have also been used to an increasing extent Pipes made of non-weldable plastics used for pipelines, as non-weldable plastics are chemically more suitable than weldable plastics in certain cases. In particular Non-weldable plastics are also suitable for the storage of reinforcements in the Pipes in the form of fabrics, fleeces and cords, preferably made of fiberglass, giving the pipe a superior strength is imparted.

The non-weldable plastics, as thermoplastics, are primarily those

Cellulose derivatives and, as hardenable plastics, especially polyester resins and ethoxylin resins. Pipes made from the plastics mentioned cannot therefore be connected to one another by welding. Even if pipes made of these plastics by gluing, cementing or otherwise, if necessary using fitting and slip-on pieces or with the help of rubber-sealed slip-on sleeves, can be connected to the pipeline ίο, so make such connections not an absolutely tight connection. This has a disadvantageous effect in many cases, where it is a good one and tight connection, as is the case with the welded connection.

The present invention is now the idea, the ends of the tubes of a non-weldable To provide plastic with a weldable plastic and thereby make it weldable to in this way to be able to weld the pipes together to form the pipeline. The one that cannot be welded, for chemical or strength reasons preferred plastic the actual support of the pipe function, while the weldable plastic at the ends of the tubes made of non-weldable plastic primarily to accommodate the weld seam serves and is supported by the non-weldable plastic pipe that it does not or if possible, comes into little contact with the medium flowing through the pipeline. In the drawing, the ends of two tubes made of non-weldable plastic are attached to them Ends made of weldable plastic in two different design options illustrated in longitudinal section, which, however, does not exhaust all possible designs.

Fig. Ι shows the first embodiment. With 1 they are two pipes made of non-weldable but very strong plastic, e.g. made of glass-reinforced polyester resin, denotes, the ends of which with a collar 2 made of a weldable plastic, for example from Polyvinyl chloride, tensile and compressive are surrounded. The collars 2 are beveled here at the front, around the to be able to connect both tubes 1 tightly to one another in the usual way by V-seam welding. The strength of the collar 2 and thus the strength of the weld 3 is such that all occurring and in the case of the non-weldable plastic pipes, permissible pressures were recorded by the weld 3 can be. In order to prevent the weldable plastic of the collar 2 with which the The aggressive medium flowing through the pipe can come into contact between the two pipes a seal 4 can be inserted at the front. The collars 2 themselves can be glued on, screwed on, be applied to the pipe ends 1 by pressing or otherwise in a manner known per se.

Fig. 2 shows the second embodiment. This consists essentially of the same parts as that of Fig. 1, except that here the connection point between the collars 5 and the tubes 6 is beveled is. With a lower waistband height, the bevel makes it possible to produce a good V-seam weld necessary height between the two collars 5 achieved. The attachment of the collar 5 on the tubes 6 is the same as that of FIG. 1.

The application and fastening of the collars or other attachments made of weldable plastic can be used in the workshop for smooth tubes, such as those produced on the extrusion press or on the construction site, so that the possibility of cutting the pipes to length for the purpose the adaptation on the construction site is given. An excellent connection between the pipe and the federal government or the extension piece is achieved if, according to the invention, the federal government or the approach- '75 piece already applies to this during the completion of the pipe, as is the case in the manufacture of Pipes made of polyester resins or ethoxylin resins with reinforcing inserts are possible using the centrifugal method is. For this purpose, a corresponding molded part made of weldable plastic is inserted into a corresponding Recess or formation of the centrifugal mold introduced, after which the polymerizable Resin mass is introduced and formed into a pipe by centrifugation. As a result of the good adhesion between the polymerizing resin composition and the weldable plastic there is an extraordinary one good connection and adhesion guaranteed.

By attaching threads, cams or the like, the required stripping strength can be achieved in the junction can be achieved in all cases.

The idea of the invention should not be limited to the two possible embodiments shown, but rather all execution options that result from the. Union of pipes Made of non-weldable plastic with an end collar or end piece made of a weldable plastic result.

The welding of the end collars or end pieces of the pipes can also be done by the aforementioned V-seam welding with additional wire in a known manner by pressure butt welding, by high-frequency welding or otherwise.

In addition to the cellulose derivatives, there are also non-weldable plastics for pipe production especially the polyester resins and the ethoxylin resins in question, but other curable synthetic resins, like the phenoplasts, are used for this. The main types of weldable plastics are Rigid polyvinyl chloride, polystyrene, acrylates and polyethylene can be considered.

Claims (7)

PATENT CLAIMS: 1. Tube made of non-weldable plastic with or without inner reinforcement inserts for the Production of pipelines for moving primarily aggressive media, characterized in that that there are end pieces, end collars or the like at its ends made of weldable plastics has, which enable a welded connection of the individual iao tubes to one another. 2. Pipe according to claim 1, characterized in that the strength of the attached to the pipe ends End pieces or end collars made of weldable plastics of those occurring herein Compressive stress is adapted. 3 pipe according to claim ι or 2, characterized in that that the parts made of weldable plastic are protected against the media flowing through the pipe by a sealing layer are. 4. A method for the production of pipes according to any one of claims 1 to 3, characterized in that that the extension pieces or end collars made of weldable plastic by gluing, screwing, pressing or otherwise with the Tube made of non-weldable plastic are connected and sealed in a tensile and pressure-resistant manner. 5. The method according to claim 4, characterized in that the approaches or end collars weldable plastic by attached threads, cams or the like. an increased Have resistance to stripping from the pipe made of non-weldable plastic. 6. The method according to claim 4 or 5, characterized in that the attachment of the extension pieces or end collars made of weldable plastic on the tube made of non-weldable plastic takes place with the manufacture of the pipes by the centrifugal process. 7. The method according to claim 6, characterized in that the extension pieces or end collars Made of weldable plastic before the start of the pipe centrifugal process in appropriate recesses or moldings of the centrifugal mold are inserted. 1 sheet of drawings 509 662 2.56